Note: Descriptions are shown in the official language in which they were submitted.
~05~'~05
'.~his invention r21ates to improvements ~ the method
obtaining blister copper by smeltlng copper matte.
~ he method of smeltIn~ copper known to dat~ is that
consi~tin~ of the following steps:
(1) The raw ore or roa~ted ore is melted by heating it at
an elev~ted temperature in a smelting furnace along with a fl~
to form a matte abounding in cuprous sulfide and slag, followed
by separating and collecting the matte;
(2) The matte is charged to a converter where air is
blown into the molten matte to convert it to blister copper in
accordance with the following reaction formula (1): :
Cu2S + 2 ~~ 2Cu + S02 (1); ..
(3) ~he molten bliste~ copper i~ charged to a refining
furnace where it is refined b~ the addition of a reducing agent
to obtai~ a refined blister copper; a~d
(4~ ~he raf ined blister copper i9 ca~t into anodes and is
electrolyzed using a copper sulfate solution as electrolyte ~nd
an electrolytic copper electrode as the cathode.,
As the above-described method of smelting copper
involves a number of steps wherein noxious waste gases are
evolved, it is desired to lessen the number of these step~.
We previously developed a method of carrying out the
electrolytical refining of blister copper by using an anodic
electrolyte suspended with particles o~ blister copper, which
~5 method is referred to as the suspension e ectrolytic method by
us ~see U.S. Patent 3,787,293 (1974~.
However, since in th~ foregoing method the~e is still
u~ed the blister copper formed in the convertsr, aftcr com-
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~OSlZOS
minuting it, the converter from which is evolved a great amount of S02 cannot
be done away with. Again, for ~his reason the smelting cannot be carried out
continuous ly .
The present invention is therefore directed at providing a method
o smelting copper by which can be produced the finely divided blister copper
that is to be used in the aforesaid suspension electrolytic method.
The inventive method of smelting copper does not use a converter and
hence can carry out the smelting continuously.
According to the present invention there is provided in the method
of smelting copper by melting a starting material of the group consisting of
copper ore and roasted copper ore in a furnace along with a flux, separating
from the melt a material of the group consisting of a matte and white metal
which abound in cuprous sulfide, and thereafter smelting the separated matte
or white metal with a member selected from the group consisting of oxygen and
an oxygen-containing gas to convert same into blister copper, the improvement
which comprises causing said matte or white metal to freely flow downwardly in
a molten state and blowing a member selected from the group consisting of air,
oxygen-enriched air and oxygen against the downwardly flowing stream of matte
or white metal thereby dividing said stream of matte or white metal into fine
particles as well as oxidatively smelting the matte or white metal to convert
same into blister copper which is simultaneously cooled and solidified before
collection as solid particulate blister copper.
A novel aspect of this invention resides in the point that the
conventional action of smelting in a converter and the comminution of the
blister copper are carried out simultaneously by blowing either air, an
oxygen-enriched air or oxygen against the stream of molten matte or white metal.
10512V5
In consequence of the above-described invention method, it
becomes possible to do away with the converting operation that was hither-
to considered necessary. Hence, the smelting can be carried out con-
tinuously. Further, when the blister copper particles obtained by the
method of this invention is used and pure copper is made by means of
suspension electrolysis, it becomes possible to do away with the refining
furnace also.
Hence, the invention method makes it possible to reduce the for-
mation of the noxious waste gas to a minimum in smelting copper. In ad-
dition, as the concentration of the waste gas can be made constant by
means of the continuous operation, the labor and equipment re~uired for
the treatment of the waste gas can be reduced.
Of the accompanying drawings, Figure 1 is a schematic drawing
illùstrating one mode of an apparatus suitable for preparing bliste~r
copper particles by means of the invention method, and Figure 2 is a graph
the curve of which shows the distribution of the particle size of the
blister copper particles obtained by the method described in the present
invention.
Next, referring to Figure 1, one mode of specifically practicing
the invention method will be described.
In the apparatus shown in Figure 1 a molten white metal vessel
1 is disposed at the uppermost part of the apparatus. A stopper 2 is
raised, and the white metal 4 is caused to flow downwardly out from a dis-
charge port 3. Air, oxygen-enriched air or oxygen 6 is jetted out from
nozzles 5 disposed below the vessel 1 and is blown against the stream of
white metal to effect its atomization. The upper half of a furnace 7 is
held at an elevated temperature ranging from 900 to 1200 C, and the
atomized molten white metal is oxidized herein by the air, oxygen-enriched
air or oxygen blown against it to be converted into molten blister copper
particles. The lower half of the furnace 7 is maintained at a low tem-
perature of below 900C., and the molten blister copper particles are
cooled here and solidified. The so prepared blister copper particles 8
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fall onto a cooling plate 9 disposed at the lower end of the furnace 7 and
are finally collected in a vessel 10. On the other hand, waste gas 11
can be conveyed from the bottom end of the furnace 7 to the side where the
recovery of heat and the sulfur dioxide is carried out.
The reaction in which the atomized molten white metal particles
are oxidized and converted to blister copper particles in the above-
described method of this invention can be represented by the aforementioned
reaction formula tl).
Accordingly, for atomizing the stream of molten white metal in
accordance with the invention method a stoichiometric quantity based on
the aforesaid reaction formula of oxygen, i.e., at least about 140 liters
of pure oxygen under standard conditions per kilogram of white metal, is
required.
It is necessary to ensure that the reaction of the atomized molten
white metal parti¢les in accordance with the aforesaid reaction formula
takes place during the time the particles are falling. Hence, for ac-
complishing this, it is best to carry out the oxidation in a short period
of time by enlarging the reactive surface area of the molten white metal
particles by making them smaller. The diameter of the molten white metal
particles is preferably not greater than 0.1 cm. The size of particles
formed by the atomization becomes smaller in proportion as the flow
velocity of gas at the atomization point, i.e., the point at which the
center line of the stream of the falling white metal and the streams of
the jetted gas meet, becomes greater. The flow velocity of gas at the
atomization point should be adjusted to be preferably in the range of 3
meters per second to 100 meters per second, and more preferably from 5
meters per second to 50 meter per second. The ~elocity of gas at the
atomization point can be adjusted by a suitable choice of the disposi-
tion, i.e., angle and distance, of the white metal nozzle and the gas
nozzles.
The reaction between the molten white metal particles and
oxygen in accordance with the aforesaid reaction formula is achieved
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extremely rapidly at elevated temperatures. Hence, the upper half of
the~ furnace at which the contact between the molten white metal particles
ancl oxygen takes place is preferably maintained at an elevated temperature.
~ t:emperature in the range of 900 - 1300C. is preferred, still more
preferred being a temperature in the range of 1000 - 1200C.
The blister copper particles that are formed by the above
reaction are preferably cooled and solidified during the time they are
falling. ~o accomplish this, the lower half of the furnace is cooled to
below 900C., and preferably to below 700 C.
The foregoing heating of the upper half of the furnace can be
suitably carried out by jetting the oxygen, air or oxygen-enriched air to
be blown against the molten white metal particles, after heating same to
200 - 400C. However, since a large amount of heat is evolved in con-
comitance with the aforesaid reaction of formula ~1), there is hardly any
need to apply heat to the furnace from the outside, especially when
o~ygen is used.
The cooling of the lower half of the furnace can be accom-
plished by natural cooling. The height of the furnace suitable for
acco~plishing the natural cooling, i.e., the distance from the gas jetting
nozzles 5 to the cooling plate 9 ranges from about 3 to 6 times the
inside diameter of the furnace. Further, the adjustment of the tem-
perature of the lower half of the furnace can be readily achieved by
adopting a method of cooling consisting of water cooling the furnace
from the outside of the refractory thereof.
For preventing the accumulation of the particles formed, the
inside diameter of the furnace is preferably enlarged towards the bottom
of the furnace. Again, it is also possible to carry out the recovery
of the reaction heat at the lower half (low temperature zone) of the
furnace. The collection of the resulting copper particles can be carried
out by oscillating the inclined cooling plate 9 with a vibrator. It is
also possible to collect the particles by placing water at the lower end
of the furnace or by flushing this part with water.
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105~;205
As iron, which accounts for a major proportion of the im-
purities contained in the molten white metal, is more easily oxidized than
copper, its oxide pnase is prepared, which separates from the copper phase
and becomes deposited on the surface of the blister copper particles.
Since this oxide phase separates from the copper particles by light
attrition, it can be removed from the product by such known procedures as
gravity concentration. Hence, even though the white metal contains a
small amount of iron, no troubles arise from the standpoint of its use.
Again, the unreacted white metal contained in the product can also be
recovered by such known methods as gravity concentration.
The following examples are given for more fully illustrating
the invention.
Example 1
A furnace of the type shown in Figure 1 having an atomization
zone of inside diameter o 50 cm and a height of 150 cm was used, and the
upper and lower halves of the furnace were held at 900C. and 700 C., res-
pectively, with electric heaters. In a crucible provided above the fore-
going urnace was melted 5 kg of white metal by heating it up to 1150C.,
which molten white metal was allowed to flow out downwardly at a rate of
1.0 kg per minute from a discharge port of inside diameter 2 mm provided
at the bottom of said crucible. Commercial grade oxygen was jetted at a
rate of 140 liters per minute (standard conditions) from 4 nozzles of
inside diameter 2 mm against the foregoing stream of w~ite metal at an
inclined angle of 22.5 deg to cause the atomization of the latter. The
flow velocity of oxygen at the atomization point was 18 meters per second.
The resulting blister copper particles were collected in a collecting
vessel via an inclined cooled plate.
The particle size distribution of the blister copper particles
obtained after screening 2.83 kg of the particles obtained as described
above (a part of the white metal was left in the crucible) showed that the
maximum value of particle size distribution was at those of particle
diameters 0.3 - 0.4 mm as shown in Figure 2. Those of particle diameter
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105~205
1.0 mm or less accounted for 64.7~ of the particles. On the other hand,
a ~ajor proportion of the particles of 3 mm or greater were lumps that
had formed as a result of the sintering of small particles.
A chemical analysis of the starting white metal and that of the
copper particles (partly intermixed with unreacted white metal particles)
obtained are shown in Table 1, below.
Table 1
Analytical Values
Cu Fe S Pb
Starting white metal 72.9% 2.5~ 18.7% 1.84%
Blister copper particles 87.7% 0.57% 9.4~ 2.22~
The reaction rate of formula (1) as calculated from these values
is 56%.
Example 2
The experiment was carried out under identical conditions as
in Example 1, except that for carrying out the atomization more effectively
an improved oxygen nozzle was used. That is, for ensuring that the area
of the point at which the stream of falling white metal and the jet stream
of oxygen meet (atomization point) becomes as small as possible, the
oxygen nozzle diameter was changed from 2 mm to 1 mm, the angle of the
white metal stream to the gaseous jet stream was changed from 22.5 deg
to 35 deg, and the velocity of the stream of oxygen at the atomization
point was increased from 18 meters per second to 36 meters per second
(the values being in all instance under standard conditions). A flow rate
of the oxygen of 140 liters per minute was used as in Example 1. As a
result, the maximum value of the particle size distribution of the
blister copper particles formed was reduced to those of diameters 0.1 -
; 0.2 mm. On the other hand, the reaction rate increased to 73%.
; Example 3
The results obtained by carrying out the electrolysis of the
blister copper particles obtained using the atomizing furnace in accordance
with the present invention will be described.
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lOSlZOS
The electrolytic cell was of disk-shape, divided by means of a
parti~ioning membrane tfilter cloth) disposed horizontally therein into
an anode chamber (the upper half) and a ca~hode chamber (the lower half).
l~e anode chamber was provided with an anode made of Ti netting, an
electrolyte outlet, a sample charging inlet and a thermometer, while the
cathode chamber was provided with a bottom of Ti plate which serves as the
cathode and an electrolyte inlet. Four hundred grams of the blister cop-
per particles (those of diameters below 0.4 mm) obtained in Example 2 were
placed in the anode chamber, while 400 grams of seed particles of pure
copper (spherical and of about 0.3 mm diameter) were placed in the cathode
chamber. An electrolyte containing 32 grams per liter of Cu2~ and 100
grams per liter of H2SO4 was introduced to the cathode chamber at a flow
rate of 30 milliliters per minute. In the meantime the electrolytic cell
was sub~ected to vertical vibration (total vibratory width 0.6 mm, 1440
cyales per minute) and horizontal oscillations teccentric radius of
oscillation 12.5 mm, 180 cycles per minute), whereupon the particles in
both chambers were kept in suspension in the electrolytes. The elec-
trolysis was carried out in this state by causing a 30-ampere direct
current to flow for 8 hours at a temperature of 40 - 50C. The cell
voltage was 1.2 - 1.5 volts. Four hours after initiation of the elec-
trolysis, 150 grams of blister copper particles were additionally charged
anew to the anode chamber.
After operating the electrolysis for 8 hours, the cathode
current efficiency as calculated from the 268-gram increase in the
Weight of the pure copper particles in the cathode chamber was 94.7~,
while the anode current efficiency as calculated from the decrease in
the weight of the total blister copper particles charged to the anode
chamber was 99.8%. The value of S that was analyzed in the matured
particles of pure copper obtained in this case was 0.001~.
_ g _
